Scientists Have Pinpointed How Zika Virus Infects the Fetus

Zika virus has dominated headlines for months, and with good reason. But the mechanics of how the virus causes brain damage in newborns has been largely a mystery — until now.

A new study from Yale University has identified how Zika virus travels from the mother to the baby, crossing the placental barrier and causing microcephaly, a dangerous birth defect that causes babies to be born with unusually small heads. For the study, researchers used three different strains of Zika virus to infect three types of cells that are found in the placenta (the organ that forms during pregnancy to help nourish the baby through the umbilical cord). The cells— Hofbauer cells, cytotrophoblasts, and fibroblasts — were taken from normal pregnancies.

What they found: Fibroblasts and Hofbauer cells were susceptible to being infected by Zika virus.

Board-certified infectious-disease specialist Amesh A. Adalja, MD, an assistant professor at the University of Pittsburgh Medical Center, explains to Yahoo Beauty why that’s a big deal: The placenta is supposed to form a barrier, protecting the baby from infections that the mother might battle. “The fact that we know that Zika is causing infection raises the question of how it was doing it,” he says. “Trying to understand the mechanisms is crucial to understand how Zika is causing fetal abnormalities.”

Study co-author Michael Simoni, MD, agrees, noting that this is a step in the right direction. “This finding helps toward understanding a critical mechanism of the virus,” he tells Yahoo Beauty. “If researchers continue down the path, it could shift how we counsel and protect those women who are at risk for Zika.”

But what does it mean, exactly? Basically, Zika virus, traveling through the pregnant woman’s blood, worms its way into the placenta, board-certified ob-gyn Pari Ghodsi, MD, explains to Yahoo Beauty. There, Hofbauer cells become infected and the virus replicates inside them. “Hofbauer cells have direct access to the fetal blood supply, so the Zika virus shimmies its way into the fetal blood supply and infects the fetus,” she says.

Unfortunately, this doesn’t change the fact that there’s no treatment for pregnant women with Zika virus. Currently, women who are infected with Zika or are at risk of exposure have increased screening done — and that’s it, Sarah Yamaguchi, MD, an ob-gyn at Good Samaritan Hospital in Los Angeles, tells Yahoo Beauty. “There is testing that is recommended to be done on all pregnant woman that are within a two- to 12-week window since exposure,” she says.

But Sherry Ross, MD, an ob-gyn and women’s health expert at California’s Providence Saint John’s Health Center, tells Yahoo Beauty that it’s important to talk to your doctor if you suspect you’ve been exposed to the Zika virus, especially if you’re pregnant. “If you suspect you have been exposed, it’s important to treat the symptoms, get plenty of rest, drink a lot of fluids, and, most importantly, get your blood tested by a perinatologist to confirm exposure,” she says.

Despite the new findings, Adalja says that there may not be a treatment for Zika virus anytime soon, especially given that 80 percent of people who are infected with the virus have no symptoms. “Sometimes findings like these don’t exactly translate into treatments, but it does help us understand why these abnormalities are occurring,” he says. “Once you understand why, you can start to think about the ways the virus attaches to these cells and what mechanisms are used — that can lead to a treatment. However, there are still a lot of questions about how to treat this.”

Simoni agrees, noting that scientists still have a long way to go. “I think we are far from a proven, effective treatment or vaccine,” he says. “But any significant information we can learn about the virus could bring us one step closer to those results.”